Merge git://ozlabs.org/~paulus/gitk
[git] / gpg-interface.c
1 #include "cache.h"
2 #include "run-command.h"
3 #include "strbuf.h"
4 #include "gpg-interface.h"
5 #include "sigchain.h"
6
7 static char *configured_signing_key;
8 static const char *gpg_program = "gpg";
9
10 void set_signing_key(const char *key)
11 {
12         free(configured_signing_key);
13         configured_signing_key = xstrdup(key);
14 }
15
16 int git_gpg_config(const char *var, const char *value, void *cb)
17 {
18         if (!strcmp(var, "user.signingkey")) {
19                 set_signing_key(value);
20         }
21         if (!strcmp(var, "gpg.program")) {
22                 if (!value)
23                         return config_error_nonbool(var);
24                 gpg_program = xstrdup(value);
25         }
26         return 0;
27 }
28
29 const char *get_signing_key(void)
30 {
31         if (configured_signing_key)
32                 return configured_signing_key;
33         return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
34 }
35
36 /*
37  * Create a detached signature for the contents of "buffer" and append
38  * it after "signature"; "buffer" and "signature" can be the same
39  * strbuf instance, which would cause the detached signature appended
40  * at the end.
41  */
42 int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
43 {
44         struct child_process gpg;
45         const char *args[4];
46         ssize_t len;
47         size_t i, j, bottom;
48
49         memset(&gpg, 0, sizeof(gpg));
50         gpg.argv = args;
51         gpg.in = -1;
52         gpg.out = -1;
53         args[0] = gpg_program;
54         args[1] = "-bsau";
55         args[2] = signing_key;
56         args[3] = NULL;
57
58         if (start_command(&gpg))
59                 return error(_("could not run gpg."));
60
61         /*
62          * When the username signingkey is bad, program could be terminated
63          * because gpg exits without reading and then write gets SIGPIPE.
64          */
65         sigchain_push(SIGPIPE, SIG_IGN);
66
67         if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
68                 close(gpg.in);
69                 close(gpg.out);
70                 finish_command(&gpg);
71                 return error(_("gpg did not accept the data"));
72         }
73         close(gpg.in);
74
75         bottom = signature->len;
76         len = strbuf_read(signature, gpg.out, 1024);
77         close(gpg.out);
78
79         sigchain_pop(SIGPIPE);
80
81         if (finish_command(&gpg) || !len || len < 0)
82                 return error(_("gpg failed to sign the data"));
83
84         /* Strip CR from the line endings, in case we are on Windows. */
85         for (i = j = bottom; i < signature->len; i++)
86                 if (signature->buf[i] != '\r') {
87                         if (i != j)
88                                 signature->buf[j] = signature->buf[i];
89                         j++;
90                 }
91         strbuf_setlen(signature, j);
92
93         return 0;
94 }
95
96 /*
97  * Run "gpg" to see if the payload matches the detached signature.
98  * gpg_output, when set, receives the diagnostic output from GPG.
99  * gpg_status, when set, receives the status output from GPG.
100  */
101 int verify_signed_buffer(const char *payload, size_t payload_size,
102                          const char *signature, size_t signature_size,
103                          struct strbuf *gpg_output, struct strbuf *gpg_status)
104 {
105         struct child_process gpg;
106         const char *args_gpg[] = {NULL, "--status-fd=1", "--verify", "FILE", "-", NULL};
107         char path[PATH_MAX];
108         int fd, ret;
109         struct strbuf buf = STRBUF_INIT;
110         struct strbuf *pbuf = &buf;
111
112         args_gpg[0] = gpg_program;
113         fd = git_mkstemp(path, PATH_MAX, ".git_vtag_tmpXXXXXX");
114         if (fd < 0)
115                 return error(_("could not create temporary file '%s': %s"),
116                              path, strerror(errno));
117         if (write_in_full(fd, signature, signature_size) < 0)
118                 return error(_("failed writing detached signature to '%s': %s"),
119                              path, strerror(errno));
120         close(fd);
121
122         memset(&gpg, 0, sizeof(gpg));
123         gpg.argv = args_gpg;
124         gpg.in = -1;
125         gpg.out = -1;
126         if (gpg_output)
127                 gpg.err = -1;
128         args_gpg[3] = path;
129         if (start_command(&gpg)) {
130                 unlink(path);
131                 return error(_("could not run gpg."));
132         }
133
134         write_in_full(gpg.in, payload, payload_size);
135         close(gpg.in);
136
137         if (gpg_output) {
138                 strbuf_read(gpg_output, gpg.err, 0);
139                 close(gpg.err);
140         }
141         if (gpg_status)
142                 pbuf = gpg_status;
143         strbuf_read(pbuf, gpg.out, 0);
144         close(gpg.out);
145
146         ret = finish_command(&gpg);
147
148         unlink_or_warn(path);
149
150         ret |= !strstr(pbuf->buf, "\n[GNUPG:] GOODSIG ");
151         strbuf_release(&buf); /* no matter it was used or not */
152
153         return ret;
154 }